Combined plug and strain relief structure



Dec. 20, 1955 Q Buss ETAL COMBINED PLUG AND STRAIN RELIEF STRUCTURE Filed Dgc. 30, 1954 c 5 m m 0 w m 6 a 2 W r mm a COMBINED PLUG STRAIN i RELIEF STRUCTURE Charles H. Bliss and Henry W. Wallace, Asheboro, N. C.,

assignors to General Electric Company, a corporation of New York 'Application December 3%, 1954; Serial'No; 473850 6 Claims. (Cl; 339 196) This application relates to a combined plug and strain relief structure and more particularly tosuch a structure adapted for use with electric blankets andthe like.

Plugs for use'with electric blankets and the like must fulfill a number of requirements, all of which are fully provided for in this combined plug and strain relief structure. For example, in order to minimize the pull exerted :such as sewing the'plug directly to the blanket'fabric.

This, of course, necessitated making the plugof some material which could be easily sewed, and also necessitated a separate stitching operation. In the plug'structure of the present invention, the blanket fabncis easily and conveniently and firmly gripped during the assembly of the component parts of the plug structure. Also it is necessary from time to time to Wash electric 'blanketswith the attendant possibility that water may; seepinto the'internal portionsof the plug structure. The plug in the present invention is so constructed that any Water which may collect in the interior of the plug during the washing operation drains easily and completely therefrom.

It is an object of this invention to provide an improved plug structure.

It is still another object of this invention to provide an improved multi-element plug structure including an improved arrangement for locating the several parts relative to each other and securing them in assembled relationship.

It is still a further object of this invention to provide an improved plug structure especially adapted for-use particularity inthe claims annexedto and forming part of this specification. In carrying out the objects of this invention in one United States Pa t element,

2,728,061 Patented Dec. 20, 1955 terminals. These two parts are further "arranged so as to provide gaps adjacent the projecting terminal pins so that any water collecting in the plug during the washing ofthe blanket drains freely therefrom. Two of the parts include cooperating hollow locating pins and recesses for assembling the two'parts in propeif' relationship, the

passage or recess in thelocattng pins being; employed merits in assembling relationship. I V I I For a better understanding of this invention reference embodiment of this invention.

t Fig. 2 is a top view of the plugstructure.

ing grooves 4, 5, 6, 7 and 8 for receiving the terminals 9,110, 11, 12 and 13 of the plug structure.

The intermediate member 3 includes a pluralitypfpassages 14, 15, 16 and 17 through which thewires 18, 19, 26) and 21, respectively connected to the plug terminals, pass to a location between the'intermediate member 3 and the lower member 2. p g

The lower member 21's provided with v a plurality of grooves 22;, 23, 24 and 25 for receiving the wires 18, 19, 20 and 21 respectively. In order to provide a strain relief for these wires, the lower element" 2 includes a plurality of serrations 26 extending transversely of the aforementioned grooves 22, ;23, 24-and 25. The cooperatingintermediate element 3 includes a corresponding "plurality of serrations 27 extending transversely of the in theassembled position of the plugelement, to be re- 7 ceived within corresponding serrations 26 and the lower I In'the assembled position of'the plug, the lower edges of the serrations 27 on the intermediate member exert a pressure on up v grooves 22, 23, 24 and 25 and thereby provide frictional strain'relief is secured. t V

v In the past it has frequently been the practice to sew the plug structure to the fabric of the electric blanket. This, of course, required a specific stitchingoperation for this purpose. Moreover, it wasnecessary to make the plug structure or atleasta flange portion thereof of" a material which could be suitably sewed, In the present invention the molded elements 1,12 and 3 are preferably formed from an acrylonitrile copolymer or similar plastic material which in its final molded state provides a hard rigid structure not suitable for sewing. In; accordance with this invention the operation of sewing is 'elirninated and the greater flexibilityin the use of'mate ials for the plug structure is achieved by mounting the plug in a simple manner in engagement with the blanket fabric.

'29. The upper surface of the member 2 is positioned directly adjacent the bottom surface ofthe blanket" ply jacent the upper surface of this blanket ply 29. It can be seen, particularly by reference to Fig. 3 that the blanket fabric '29 is firmly gripped by the cooperating serrations 'I26 and27 'of the members'z'i'and 3'r'e spec tively when "the' el'emerits of the "plug structure are in their assem- "bled relationship. The plug is"thereby held firmly in 26 and 27 extend over only a portion of the surface of the members 2 and 3, it will be apparent that for more complete gripping of the blanket fabric these serrations could be arranged to cover a greater portion or the entire surface of the members 2 and 3.

In order to assemble the parts in proper relationship the lower element 2 includes two outer openings 30 within which are received two depending members or pins (not shown) molded integrally with the intermediate member 3. These pins and the cooperating openings 30 insure the assembling of the members 2 and 3 in proper relationship. In order to assemble the members 1 and 3 in proper relationship and further to facilitate the complete assembly of all three elements in the final plug structure, the upper member 1 is formed to include two hollow or recessed locating pins 31 and the intermediate member 3 is correspondingly formed to include two cooperating recesses or passages 32 extending therethrough. In the assembled relation of the parts 1 and 3, the pins 31 are snugly received within the recesses or openings 32 thereby fixing these two parts, and also fixing, of course, the terminals 9, 10, 11, 12 and 13 and their associated elements in proper cooperating grooves 4, 5, 6, 7 and 8 and 4a, 5a, 6a, 7a and 8a in the members 1 and 3.

For facilitating the final assembly of the members 1, 2 and 3 into the completed plug structure, the locating pins 31 are specifically made hollow, as indicated above,

that is each is provided with a passage 33 extending therethrough or with a recess therein. In the form of invention illustrated, each of the locating pins 31 includes a recess extending upwardly from the bottom end thereof. Because of the fixed relationship of the members 2 and 3 by means of the pins and openings 30 previously referred to, the recesses 33 are directly in line with openings 34 provided in the bottom member 2. Thus the locating pins 31 serve not only to fix the members 1 and 3 in proper relationship but they also provide passages or recesses for receiving fastening members to complete the assembly of all three members of the plug structure.

In the form of invention shown in Fig. 4 the fastening devices are in the form of self-threading screws adapted to be received in threaded engagement with the recesses 33 in the member 1. Access to the screw heads can be easily obtained by reaching between the plies 28 and 29 of the blanket before the binding is placed on the ends of the blanket. While recesses 33 have been described above, it will be apparent that passages extending completely through the locating pins 31 could be employed. Also, other fastening devices could be utilized in place of the screws 35; for example, where passages extending completely through the pins 31 are employed, rivets extending through these passages could be used.

It will be apparent, of course, that from time to time it is desirable to wash electric blankets or other electric bed covers. The plug structure, for reasons discussed above, is firmly fixed in engagement with the blanket fabric, and it is undesirable to remove the plug, which would effect a substantial disassembly of the blanket wiring elements, for the washing operation. Accordingly the blanket, including the plug, is usually subjected to the washing operation. It is possible for water to seep into the interior of a plug under such circumstances and to be trapped therein. In order to avoid the disadvantages of such water seepage, the plug structure of the present invention is formed as best shown in Fig. 1 to provide specifically large gaps adjacent the terminals 9, 10, 11, 12 and 13 extending into the interior of the plug structure. Thus, as shown in Fig. l the portions of the plug members 1 and 3 between the terminals 9 and 13 at the terminal end of the plug are made somewhat thinner than the outer portions of these plug members. The members 1 and 3 firmly engage each other along the co- 5 operating outer surfaces or perimeters 36, but the surfaces 37 and 38 of the members 1 and 3 respectively are spaced a substantial distance from each other in the regions between adjacent terminals. This construction provides passages 39 of substantial size in these regions so 0 that any water which may collect within the interior of the plug during the washing operation easily and automatically drains therefrom through these passages 39. Hence no water is trapped within the plug structure.

While some of the features of this invention have been described by particular reference to bed covers, it will be apparent that the invention in these respects is equally applicable to other devices in which wiring and a plug is used in association with some fabric.

While a specific embodiment of this invention has been shown and described, it is not desired that the invention be limited to the particular construction shown and de scribed and it is intended by the appended claims to cover all modifications within the spirit and scope of this in vention.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. A multi-element plug comprising a top molded plastic member, a bottom molded plastic member and an intermediate molded plastic member, said top and intermediate members having cooperating recesses for receiving terminals of the plug, said intermediate member including passages therethrough for receiving wires extending to said terminals, two of said members including cooperating locating pins and recesses respectively for holding said members in proper assembled relationship, said pins including recesses therein, the third of said members including openings adapted to register with said pin recesses, and fastening means extending through said openings and into said pin recesses for holding all three members in 40 assembled relationship.

2. A multi-element plug comprising a top molded plastic member, a bottom molded plastic member and an intermediate molded plastic member, said top and intermediate members having cooperating recesses for receiving terminals of the plug, said intermediate member inmembers in assembled relationship.

cluding passages therethrough for receiving Wires extending to said terminals, said top member including a plurality of depending locating pins, said intermediate member including corresponding recesses for receiving said 0 pins to hold said members in proper assembled relationship, said pins including recesses therein, said bottom member including openings adapted to register with said pin recesses, and fastening means extending through said openings and into said pin recesses for holding all three 3. The combination of claim 1 wherein said bottom member includes passages on the interior surface for receiving said wires and wherein said intermediate member and said bottom member include cooperating serrations extending transversely of said passages whereby when said intermediate member and said bottom member are in assembled relationship, said serrations on said intermediate member engage said wires to provide strain relief.

4. A plug structure adapted for use with a fabric and associated wiring comprising a top molded plastic member, a

bottom molded plastic member, and an intermediate molded plastic member, said bottom and said intermediate member including serrations extending transversely along the cooperating surfaces thereof, at least one ply of said blanket being received between said bottom member and said intermediate member and being engaged by said cooperating serrations, and means for fastening said members in assembled relationship whereby said blanket ply is firmly gripped by said cooperating serrations.

'5 5. plug structure adapted for use with a fabric and associated wiring comprising a top molded plastic mem- 6. A plug structure adapted for use with a washable ber, a bottom molded plastic member, and an intermefabric comprising a top molded plastic member, a bottom diate molded plastic member, said top and intermediate molded plastic member, and an intermediate molded plasmembers having cooperating recesses for receiving tertic member, said top member and said intermediate memminals of the plug, said intermediate member including 5 her including cooperating recesses for receiving plug terpassages therethrough for receiving wires extending to minals, means for holding said members in assembled resaid terminals, said bottom member including passages on lationship, said top member and said intermediate memthe interior surface thereof for receiving said Wires, said her engaging each other along a surface extending along cooperating serrations extending transversely of said pas- 10 member and said intermediate member at the end adjasages, at least one ply of said blanket being received becent sa1d plug terminals being spaced from each other in tween sa1d bottom member and said intermediate memthe regions between ad acent terminals to provide gaps her, said cooperating serrations gripping said blanket ply for drainage therethrough of any water collecting in the therebetween, sa1d serrations on sa1d intermediate meminterior of the plug when the fabric is Washed.

ber further engaging said wires to provide strain relief, 15

and means for fastening said members in assembled re- No references citedlationship whereby said blanket is gripped by said cooperating serrations and said serrations on said intermediate member are held in firm engagement with said wires. 

